The invention relates to a device for the manual sharpening of knives and other blades having exchangeably held carbide plates.
Devices for the manual sharpening of knives and other blades are already known in different aspects:
For instance, the devices in accordance with DE 197 03 807 C1 or with U.S. Pat. No. 5,588,340, for example, use only one carbide plate with which a knife blade first has to be sharpened from the one side of the blade and then from the other side. Such sharpening devices having a single carbide plate are suitable for the sharpening of different blade types, e.g. of knives, scissors, tools of different types or also ski edges. However, there is the risk that the carbide plate for the sharpening is applied at an incorrect angle or that canting takes place, which results in unsatisfactory sharpening results.
On sharpening with two crossed carbide plates such as are known from U.S. Pat. No. 6,142,038; U.S. Pat. No. 5,291,805; or U.S. Pat. No. 3,149,506, both sides of a blade are processed simultaneously at a pre-determined appropriate angle. One error source in handling is thus precluded. These devices are in particular suitable for the sharpening of smooth knives without a serrated edge.
Since it is always the same position, namely the V-shaped sharpening zone in the crossing region of the two carbide plates, which is strained, wear phenomena of the carbide plates in the sharpening zone are inevitable in the long term.
For this reason, the carbide plates in accordance with U.S. Pat. No. 6,142,038; U.S. Pat. No. 5,291,805; or U.S. Pat. No. 3,149,506 are held exchangeably so that an exchange or replacement of plates which have become unusable can be made. The carbide plates are inserted into suitably shaped recesses in the device body which fix them downwardly and laterally. For the remaining fixing, the plates in accordance with U.S. Pat. No. 6,142,038 are screwed individually and the plates in accordance with U.S. Pat. No. 5,291,805 or U.S. Pat. No. 3,149,506 are secured by an angled part which is in turn secured to the device body by a screw. In accordance with U.S. Pat. No. 6,142,038, the carbide plates are moreover shaped as rectangles and the recesses are arranged so that, in the case of wear at one position, the same plates can be used again at another position when replaced with one another and/or turned.
The fixing of the carbide plates using a screw shown in U.S. Pat. No. 6,142,038; U.S. Pat. No. 5,291,805; and U.S. Pat. No. 3,149,506 has the disadvantage that, on the exchange of plates by the user, the suitable screwing tool is not always to hand; that, as on the first assembly during manufacture, the holding together of the plurality of still loose individual parts and the application of the screws is a comparatively time-consuming and arduous task requiring the right feel; and that in the course of time the screws can seize unreleasably, on the one hand, or can also become loose, on the other hand.
The sharpeners in accordance with U.S. Pat. No. 5,291,805 or U.S. Pat. No. 3,149,506 are evidently provided for a free guidance of the device over a blade; since knives to be sharpened frequently also cannot be placed onto a work surface in a stable manner due to non-straight handle shapes or back shapes, canting, the sliding off of the device or of the blade, unnecessary use of force or even injuries can occur.
While U.S. Pat. No. 6,142,038 shows an additional part for the secure application of the sharpening device during sharpening, this gives the device a less practical shape.